JP2018044364A - Windbreak snow fence - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive windbreak snow fence that relieves a snowdrift caused on the leeward side, has high effect of lessening wind speed, and is capable of securing visibility.SOLUTION: A lower stage from a height of about 2/3 of a fence height is formed as an unperforated plate 10, and a windbreak snow plate of upper-lower stages 20 at a height of about 2/3 to about 5/6 of the height of the fence height is composed of swelling parts being line symmetry in a shape of a vertical cross section. One of the swelling parts has an inclined plane whose an upper part is inclined toward upwind, and a large number of through-holes are provided in the inclined plane. The opposite side of the swelling part is formed as an unperforated hole, and a hole opening ratio of the whole upper-lower stages 20 is set to about 20%. A windbreak snow plate of the upper-upper stage 30 up to an upper end from a height of about 5/6 of the fence height comprises the swelling parts being line symmetry in the shape of the vertical cross section, and one of the swelling parts has an inclined plane whose upper part is inclined toward the upwind. A large number of large through-holes are provided in the inclined plane, and small through-holes are provided on the opposite side of the swelling part, where the hole opening ratio of the whole upper-upper stage 30 is set to about 40%.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a windbreak snow fence that is installed along a road or track to prevent a snowdrift from being formed on the road or track in a snowy area and to ensure visibility.

  In snowy areas, seasonal winds blow mainly from the north to the west during the winter, preventing snowdrifts from forming on the road surface and ensuring visibility and ensuring traffic safety. A windbreak snow fence is installed along the road.

  Various types of windbreak snow fences have been proposed, but they are mainly installed on the windward side of the road and blown off by blowing wind on the road surface, and snow is stopped and accumulated on the windward side to the road. There is a blow-off type to reduce the spraying.

  In the former blow-off type, a plurality of upper and lower rectifying plates are installed on the road shoulders on the shoulders of the road so that the wind from the windward is directed downward. Instead, it sprays on the road surface and blows off the snow that is about to accumulate on the road surface. In addition, the latter blowing type protects the road by blocking and slowing down the snow blowing on the road, not the current plate, and it is common to provide windbreak snow boards with many small holes between the columns. It is.

  However, since the snowstorm and wind strength generated by the weather are not always the same, there are cases where the above-mentioned targeted effect cannot be obtained, and conversely, there is a problem that a snowdrift occurs. Also, when there is little or no snow accumulation on the windward side of the snow fence, it does not cause snow accumulation or rolling up on the road, preventing road traffic troubles due to snow, and on the shoulder. Blow-type snow fences that can be installed are desired.

  As an example, in Japanese Patent No. 3711470, in a snow fence with a total height of about 5 m, a snow plate is vertically raised from the bottom to a height of 3.2 m, and there is a horizontal portion toward the windward. There is a 0.6m-long creeping part with the snowbreaker board tilted at an angle of 45 degrees, and the snowbreaker board is tilted at an angle of 60 degrees to the leeward side on the opposite leeward side. Shown is a blow-off type snow fence made up of three parts, a guide part of 1.5 m in length that is guided to a distance. In addition, there is a blown-type snow fence that has holes with a diameter of several centimeters evenly formed on the snow-preventing plate of the creeping part or on the snow-preventing part of the guiding part so that the total opening ratio is 20 to 40%. It is shown.

  According to this invention, when there is little snow, it functions well as a blow-off type snow fence, and when the amount of snow exceeds a certain amount, it blows wind and snow far away and works to prevent snow from accumulating on the road Yes.

  Increasing the fence height with an overall height of about 5 m is a major factor for improving wind and snow performance. However, increasing the height of the fence results in a high cost because it is necessary to increase the strength because a large wind load is applied to the pillar and foundation. In addition, if the structure of the column is complicated, such as the creeping part and the guiding part, there is a problem that the manufacturing cost increases. Therefore, there is a method in which the shape of the support is simplified and the windproof snow plate is devised to improve the windproof snow performance.

  As an example, Japanese Patent No. 4096077 discloses a column base that is embedded in the ground at predetermined intervals along a road, a column that is erected on each column base, and a bridge column that is installed between the columns. In a snow fence composed of a plurality of snow plates arranged in the vertical direction, a lower snow plate group provided on the lower side between the columns is composed of a plurality of non-perforated plates, and an intermediate snow plate group provided in the middle is It is composed of a plurality of perforated plates having a porosity of about 30 to 40%, and the upper snow protection plate group provided on the upper side is composed of one or a plurality of mesh panels having a porosity of about 70 to 90%. Shown is a blown snow fence characterized by

  According to this invention, the middle part snow protection board group arranged in the middle part of the support column is composed of a large number of perforated boards having a transmittance of about 30 to 40%, and the upper snow protection board group arranged on the upper side is By constructing one or more mesh panels with a transmittance of about 70 to 90%, the wind load on the snow fence is made as small as possible and the center of gravity is lowered, so the column base is enlarged. It is said that the fence height can be raised to about 7m, which has high wind and snow protection effect. Moreover, the snow-proof board arrange | positioned at the upper part side of a support | pillar is comprised with the mesh-like panel of the transmittance | permeability of about 70-90%, and since a landscape can be visually observed through a mesh-like panel, the feeling of pressure given to a driver is minimized. It can also solve the problem of landscape obstruction.

  Furthermore, although it is said that the height of the fence can be increased to a height of about 7 m, which has a high windproof and snowproof effect, without increasing the size of the column base, increasing the height of the fence increases the strength. It becomes expensive because it is necessary. On the other hand, there is a method of improving the wind and snow protection effect without devising the wind and snow plate without increasing the height of the fence.

  As an example, in Japanese Patent No. 5579208, a strip-shaped windbreaking snowboard which is long in the horizontal direction is vertically arranged between pillars standing at intervals so as to form a fence against the windward in winter. In the windbreak snow fences arranged side by side, windproof snowboards with no holes in the middle from the middle height or fine holes that do not allow wind to pass through are used. It consists of a bulging part with line symmetry and a straight attachment part at both ends of the bulging part. It is fixed to the column with the straight attachment part, and one of the symmetric bulging parts is inclined upward toward the windward side. While having a straight or curved inclined surface, the inclined surface is provided with a number of through-holes in the longitudinal direction of the windproof snowboard, and the opposite side of the bulging portion is made non-perforated or has fine holes that are difficult to pass air. The wind blown from the windward from the middle height to the upper stage is inclined by the windbreak snowboard. Windproof Yukisaku varying the direction of air flow upward while passing through the hole of the surface is shown.

  According to this invention, since the windproof snow plate provided with fine holes that are not perforated from the middle of the windproof snow plates arranged in a plurality of stages on the upper and lower sides or provided with fine holes that do not allow wind to pass through, wind and snow are not allowed to pass. The airflow passing through the upper windbreak snowboard changes upward, and the airflow passing through the upper stage merges with the airflow above the windbreak snow fence and blows away far away, so the snow falling to the leeward side decreases and snowdrift occurs It is said that it can be eased. In addition, since one of the symmetric bulges of the windbreak snowboard is provided with a large number of through holes, the intimidating feeling given to the vehicle driver can be reduced, and the airflow can reduce the load caused by the wind. Therefore, the cost of windproof snow fences can be reduced.

Japanese Patent No. 3711470 Japanese Patent No. 4096077 Japanese Patent No. 5579208

  In the technique of Patent Document 3 above, the fence height is about 3 m, and the cost can be reduced compared to the technique of Patent Document 1 and the technique of Patent Document 2, but the airflow that has passed through the upper stage merges with the airflow of the upper layer of the windbreak snow fence. Although it blows through, the snow falling to the leeward side combined with the low fence height causes more snowfall on the leeward side of the fence due to more snow than the techniques of Patent Document 1 and Patent Document 2.

  Installation of a windproof snow fence is generally expensive because of its long installation length. In order to reduce the cost, it is desirable that the windbreak snowboard has a structure that allows the wind to pass to some extent so as not to apply a load to the pillars and foundations. However, the problem of snowdrift and the securing of visibility as described above often occur by allowing the wind to pass, and it is difficult to achieve both with conventional techniques.

  In view of the above, an object of the present invention is to provide a windproof snow fence that can alleviate a snowdrift occurring on the leeward side, has a high effect of reducing the wind speed, can ensure visibility, and is low in cost.

  In order to solve the above-mentioned problem, the windbreak snow fence according to the first aspect of the present invention has a strip-shaped windbreak snowboard which is long in the horizontal direction between the columns 5 which are vertically arranged with a space therebetween. In the wind-proof snow fence 1 that is arranged in multiple stages above and below to form a fence against the fence, the lower stage is set to the non-perforated plate 10 from the height of about 2/3 of the fence height, and about 2/3 of the fence height. The windproof snowboards of the upper and lower tiers 20 having a height of about 5/6 from the height of the vertical section are composed of a bulging portion 21 whose shape of the vertical section is axisymmetric and a straight mounting portion 22 at both ends of the bulging portion 21. One of the symmetric bulging portions 21 has a straight or curved inclined surface that is inclined upward toward the windward, and a plurality of through holes 23 are provided in the inclined surface over the longitudinal direction of the windbreak snowboard. The other side of the bulging part 21 is non-perforated, and the opening ratio of the entire upper and lower tiers 20 is about 20%, and is blown from the windward to about 5/6 to about 5/6 of the fence height. Wind When passing through the through-hole 23 on the inclined surface of the windbreak snowboard, the direction of the airflow is changed upward, and the windbreak snowboard of the upper upper stage 30 from the height of about 5/6 to the upper end of the fence is A bulging portion 31 whose vertical cross-sectional shape is line symmetric and straight attachment portions 32 at both ends of the bulging portion 31, and one of the line symmetric bulging portions 31 is a straight line inclined upward toward the windward or In addition to the curved inclined surface, the inclined surface is provided with a large number of large through holes 33 in the longitudinal direction of the windbreak snowboard, and the opposite side of the bulging portion 31 is provided with small through holes 34, and the entire upper upper stage 30 is provided. The opening rate is about 40%, and the wind blown from the windward to the height from about 5/6 of the fence height to the upper end is the large and small through holes 33 and 34 on the inclined surface of the windbreak snowboard. The direction of the airflow is changed upward when passing through.

  According to the first aspect of the present invention, the non-perforated plate 10 is used as the lower plate from the height of about 2/3 of the fence height of the windproof snowboards arranged in a plurality of stages above and below, so that wind and snow can pass through. However, the airflow passing through the windbreak snowboards of the upper and lower tiers 20 and 30 changes upward, and the airflow that passes through the upper and lower tiers 20 and 30 merges with the airflow in the upper windbreak snow fence and blows away to the far side. The snow falling to the leeward side can be reduced to reduce the occurrence of snowdrift.

  In the same way, the lower wind is blocked from about 2/3 of the height of the fence, and the airflow passing through the upper and lower tiers 20 and 30 changes direction upward, so the wind speed under the windbreak snow fence is sure. Visible to ensure visibility.

  Moreover, since the support | pillar 5 stood vertically, the structure of the support | pillar 5 is simple and can reduce the cost of a wind-proof snow fence.

FIG. 1 is a front view of a windproof snow fence according to the first embodiment. 2 is a right side view in which a part of FIG. 1 is cut away. FIG. 3 is a partially enlarged view of the upper and lower stages 20 of FIG. 4A is a partially enlarged view of FIG. 3, and FIG. 4B is a side view thereof. FIG. 5 is a partially enlarged view of the upper upper stage 30 in FIG. 6A is a partially enlarged view of FIG. 5, and FIG. 6B is a side view thereof. FIG. 7 is a windproof snow fence installation plan according to the first embodiment. FIG. 8 is a windproof snow fence installation completion photograph (desired from the leeward side) according to Example 1. FIG. 9 is a photograph of the wind direction anemometer installation completion of the weather observation equipment of Example 1. FIG. 10 is a photograph of the completion of installation of the snow depth meter of the meteorological observation device of Example 1. FIG. 11 is an overall photograph according to the first embodiment. FIG. 12 is a photograph of the snowdrift situation (desired from the leeward side of the fence) according to the performance evaluation of Example 1. FIG. 13 is a photograph of the snowdrift situation (desired from the windward side of the fence) according to the performance evaluation of Example 1. FIG. 14 is a photograph of the snowdrift situation (desiring a longitudinal direction from the southwest side of the fence) according to the performance evaluation of Example 1.

  The purpose of providing a windproof snow fence that relaxes the puddle on the leeward side, has a high effect of reducing the wind speed, can ensure visibility, and is low in cost. In the windbreak snow fence 1 in which a long strip-shaped windbreak snowboard is arranged side by side so as to form a fence against the windward in winter, there is no bottom from the height of about 2/3 of the fence height. The windproof snowboard of the upper and lower tiers 20 having a height of about 2/3 to about 5/6 of the height of the fence as the perforated plate 10 has a bulging portion 21 whose vertical cross-sectional shape is axisymmetric, and a bulging portion And the linearly-attached bulging portion 21 on both ends of the portion 21 has one of the linearly symmetric bulging portions 21 having a straight or curved inclined surface inclined upward toward the windward side, and a windproof snow plate on the inclined surface A large number of through-holes 23 are provided in the longitudinal direction, the opposite side of the bulging portion 21 is not perforated, and the opening ratio of the entire upper and lower tiers 20 is about 20%. When the wind blown from the windward from about 2/3 to about 5/6 passes through the through-hole 23 of the inclined surface of the windbreak snowboard, the direction of the airflow is changed upward, and the fence The windproof snowboard of the upper upper stage 30 from the height of about 5/6 to the upper end is composed of a bulging portion 31 whose vertical cross-sectional shape is axisymmetric and a straight mounting portion 32 at both ends of the bulging portion 31. And one of the line-symmetric bulging portions 31 has a straight or curved inclined surface that is inclined upward toward the windward, and the inclined surface has a large number of large through holes extending in the longitudinal direction of the windbreak snowboard. 33 is provided, and a small through hole 34 is provided on the opposite side of the bulging portion 31 so that the opening ratio of the entire upper stage 30 is about 40%, and the height from the height of about 5/6 of the fence height to the upper end is set. This was realized by changing the direction of the air flow upward when the wind blown from the wind passes through the large and small through holes 33 and 34 on the inclined surface of the windbreak snowboard.

  Embodiment 1 of the present invention will be described below with reference to the drawings. 1 is a windproof snow fence according to Embodiment 1 of the present invention.

  This windbreak snow fence 1 is installed along roads and tracks so as to be a fence against the windward in winter, and is installed to prevent the formation of snowstorms and puddles and ensure traffic safety It is.

  Under the ground G, concrete foundations F that serve as foundations for the columns 5 are embedded at equal intervals, and the columns 5 are fixed vertically on the concrete foundations F. A plurality of required pillars 5 are arranged in a row, and a strip-shaped windproof snowboard that is long in the horizontal direction is arranged vertically between the pair of pillars 5 to constitute a fence. In this embodiment, the height from the ground G to the upper end of the columns 5 is about 4 m, and the interval between the columns 5 is about 3 m.

  A non-perforated plate 10 as a wind-proof snow plate is provided side by side from the middle height of the wind-proof snow fence 1 to the ground G. The non-perforated plate 10 is a rectangular strip-like steel plate that is long in the horizontal direction, and is bent and formed into a line-symmetric trapezoidal shape near the middle of the vertical cross section, and vertical straight mounting portions are provided at both upper and lower ends, Long holes are provided at the four corners of the plate 10 and fixed to the column 5 with bolts and nuts. The non-perforated plate 10 shown in this embodiment is a steel plate having a thickness of 1.6 mm. The vertical (short side) is about 250 mm, the horizontal (long side) is about 3000 mm, and the distance from the straight mounting portion to the trapezoidal convex end is about 70 mm. From the height of 2.5m, which is about 2/3 of the height of the fence, it was provided side by side without gaps of 10 steps. Further, the trapezoidal convex portion of the non-perforated plate 10 is arranged so as to be convex toward the leeward side of the windbreak snow fence 1.

  No holes or the like are provided in the bent portion of the non-perforated plate 10. Further, by bending the vertical cross section into a convex shape, the cross-sectional performance is improved, and even if the non-perforated plate 10 is made of a thin steel plate, it is possible to obtain a strength that is not bent by wind.

  On the other hand, the windbreak snowboards of the upper and lower tiers 20 having a height of about 2/3 to about 5/6 of the height of the fence of the windbreak snow fence 1 are attached to the column 5 from a height of 2.5 m to 3.25 m. Set up side by side. The windproof snowboards of the upper and lower tiers 20 are made of the same material and size as the non-perforated plate 10, and are composed of a bulging portion 21 whose vertical cross-sectional shape is axisymmetric and a straight mounting portion 22 at both upper and lower ends of the bulging portion 21. . In the present embodiment, the windproof snowboards of the upper and lower tiers 20 are provided side by side with a gap of three steps from a height of 2.5 m from the ground G to 3.25 m.

  Like the non-perforated plate 10, the bulging portion 21 is formed by bending the vicinity of the middle of the vertical section into a line-symmetric trapezoidal shape, and from the center to the top, a large number of round holes with a diameter of 18 mm as through holes. 23 is densely provided in the longitudinal direction of the windproof snowboard of the upper and lower tiers 20, and the lower portion is made non-perforated so that the opening ratio of the entire upper and lower tiers 20 is about 20%. The convex direction of the bulging portion 21 of the windproof snowboard of the upper and lower tiers 20 is the same as the non-perforated plate 10 and is convex to the leeward side, and the bulging portion 21 is bent into a trapezoidal shape, so the round hole 23 is on the windward side. A large number of inclined surfaces are inclined upward. In addition, long holes 24 are provided in the straight mounting portion 22 at positions corresponding to the four corners of the windproof snowboard of the upper and lower tiers 20, and are fixed to the column 5 with bolts and nuts.

  As a result, when the wind blowing from the windward to the height of about 5/6 from the height of about 2/3 of the fence height passes through the round hole 23 on the inclined surface of the windproof snow plate of the upper and lower tiers 20, the hole is opened. Since the rate is about 20%, the direction of the airflow changes strongly upward although it is a small amount.

  In addition, the windproof snowboard of the upper upper stage 30 from the height of about 5/6 of the height of the fence of the windbreak snow fence 1 to the upper end is provided side by side on the column 5 from the height of 3.25 m to 4 m. The windproof snowboard of the upper upper stage 30 is made of the same material and size as the non-perforated board 10, and includes a bulging portion 31 whose vertical cross-sectional shape is axisymmetric, and straight mounting portions 32 at both upper and lower ends of the bulging portion 31. . In the present embodiment, the windproof snowboards in the upper upper stage 30 were provided side by side with a gap of three stages from a height of 3.25 m to 4 m from the ground G.

  Like the non-perforated plate 10, the bulging portion 31 is formed by bending the vicinity of the middle of the vertical cross section into a line-symmetric trapezoidal shape, and has a large number of 18 × 28 mm as large through holes from the center to the upper side. The long round holes 33 are densely provided in the longitudinal direction of the windproof snowboards of the upper and lower stages 30, and a large number of round holes 34 having a diameter of 14 mm as small through holes are provided on the opposite side of the bulging part 31. Is set to about 40%. The convex direction of the bulging portion 31 of the windproof snowboard of the upper upper stage 30 is the same as that of the non-perforated plate 10 and is convex leeward, and the bulging portion 31 is bent into a trapezoidal shape. A large number of round holes 34 are provided on the inclined surface inclined upward toward the upwind, and the inclined surface inclined downward toward the windward side. It should be larger than the porosity. The straight mounting portion 32 is provided with long holes 35 at positions corresponding to the four corners of the windproof snow plate of the upper upper stage 30 and is fixed to the column 5 with bolts and nuts.

  As a result, when the wind blown from the windward to the height from about 5/6 of the fence height to the upper end passes through the elongated hole 33 and the round hole 34 on the inclined surface of the windbreak snowboard of the upper upper stage 30 Since the hole area ratio is about 40%, the airflow direction changes weakly in a large amount and upwards.

  Next, experiments and results conducted from 2015 to 28 in order to verify the effect of the windproof snow fence according to the present invention will be described.

In order to verify the effect of the windbreak snow fence according to the present invention, the present inventors performed measurement by installing the windbreak snow fence in Ishikari City, Hokkaido.
Date of fence installation: December 21, 2015 Observation period: December 21, 2015 to March 3, 2016 Fence height: H = 4.0 m
Installation extension: L = 48m
Installation direction: north-northeast-south-south-west (direction of fence longitudinal, main wind direction during snowstorm: west-northwest)
Snow measurement range Windward: Range of fence ~ 20m Fence downside of fence: Range of fence ~ 40m (10H range)
Snow measurement line: 5 lines (see Fig. 7)
The windward is also measured with the same line. Measurement of the leeward side is important for snowproof performance evaluation. The windward side measurement is a reference for evaluation of the leeward snowdrift evaluation (reference value. Whether or not the snow hill has reached the perforated part, whether there is a lot of windward snowfall supplementation empirically, etc.) Here, no data analysis is performed.
Meteorological observation equipment: Wind anemometer (installed on December 21, 2015)
Snow depth meter (installed on January 19, 2016)

  Fig. 7 is a plan view of the windbreak snow fence installation plan, Fig. 8 is a photo of the windbreak snow fence installation status, Fig. 9 is a photo of wind direction anemometer installation status, Fig. 10 is a photo of the snow depth gauge installation status, As shown in FIG.

Table 1 shows the snow observation data on February 29, 2016, and the snow graph is shown in Table 2. In addition, photographs of the local snowdrift situation are shown in FIGS.

  Here, snow observation is carried out on all five lines, but the snow prevention effect is evaluated by interpolation 2 (middle between the center and the north side) based on the “determination of performance evaluation line” described later (see the figure). 12). The natural snowfall on this day is 0.90 m, and the snowdrift performance evaluation is expressed by an increase / decrease from 0.90 m.

  The performance evaluation is organized below.

  The maximum snowdrift was + 0.50m (snow depth of 1.40m) in the immediate vicinity of the fence (0H). Looking at the windward side of this line, the snow hill reaches the perforated area. Usually, when the snow hill reaches the perforated area, the leeward puddle develops rapidly, but the local puddle is very small. Further, at a position 1.0 m from the fence, it is very small as +0.35 m, and not only the height direction but also the transverse direction is suppressed to a very narrow range.

  Other than 0H, 0.5H is + 0.13m, 1H is -0.03m, 2H is 0.14m, 3H to 10H is -0.15m to -0.40m, and exhibits a sufficient effect of suppressing the puddle. Yes.

"Determination of performance evaluation line"
The snowdrift in the snow fence is affected by the edge of the fence. When evaluating the performance of snow fences, it is necessary to avoid the edge affected range. National Development Research Institute (former Independent Administrative Institution) Civil Engineering Research Institute Cold Civil Engineering Research Institute Priority Project Report 7.3 A study on the performance evaluation of snow prevention facilities (2007 Kajiya et al.) It can be remarkably confirmed that it is influenced by the end effect in the range of 30 m from the edge of the fence at = 5 m. The fence height according to the present embodiment is H = 4 m. In consideration of the fence height ratio in the end effect range, 4/5 × 30 = 24 m is a guide when H = 4 m.

  In the winter observation of this example, there was no puddle due to the end effect as of January 8, 2016, and a puddle due to the west wind was formed over the next observation day, January 13. The puddle caused by the end effect once formed continues to grow without disappearing. The snowdrift caused by the end effect is formed from the south end to the snow fence center throughout the observation period, and the influence disappears from the center to the interpolation 2. For this reason, the performance evaluation was performed by line interpolation 2 which is in the middle between the center of the snow fence and the north end.

  The embodiment of the present invention is determined by narrowing down combinations of windproof snowboards using a wind direction and wind speed numerical simulation system, and observing a snowdrift situation by a wind tunnel experiment using activated clay. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist.

  For example, in the embodiment, an example in which the fence height is about 4 m and the non-perforated plate 10 is 10 steps, the upper and lower steps 20 are three steps, and the upper upper step 30 is three steps is shown. It is possible to have 4 steps for the upper and lower steps 20 and 4 steps for the upper and upper steps 30 and a fence height of about 5 m. Further, the upper and lower stages 20 and the upper upper stage 30 do not have to have the same number of stages, and the upper and lower stages 20 may have four stages and the upper upper stage 30 may have three stages.

  Further, in the embodiment, an example in which the non-perforated plate 10 having no hole is provided from the height of about 2/3 of the fence height is shown, but it is not necessary to block the wind from the windward and easily pass it. The visibility may be improved by appropriately providing fine holes with a diameter of about 3 mm.

  Further, in the embodiment, a large number of round holes 23 having a diameter of 18 mm as through-holes are provided densely in the longitudinal direction of the windproof snowboard of the upper and lower tiers 20 and the lower portion is not perforated so that the entire upper and lower tier 20 has an opening ratio of about Although an example of 20% is shown, it is only necessary to block the wind below the bulging portion 21 and change the air flow upward. Prospects may be improved by appropriately providing holes. Moreover, although the round hole 23 showed the example which is a round hole, a long hole shape etc. may be sufficient.

  Further, in the embodiment, the bulging portions 21 and 31 are formed by bending the vicinity of the middle of the vertical section of the windproof snowboard of the upper and lower tiers 20 and 30 into a line-symmetric trapezoidal shape, but in a semicircular shape It may be formed into a convex shape.

  Further, in the embodiment, the example in which the convex direction of the bulging portions 21 and 31 of the windproof snowboards of the upper and lower tiers 20 and 30 is convex toward the leeward side, but the upper side is inclined toward the leeward side. Since it is sufficient if the inclined surface has a through hole, it is needless to say that the same effect can be obtained by forming a convex shape toward the windward, providing a large number of through holes below the line symmetry, and arranging a plurality of stages vertically.

1 Windproof snow fence 5 Prop
10 Non-perforated plate
20 Top and bottom
21 bulge
22 Straight mounting section
23 Round holes as through holes
30 Upper
31 bulge
32 Straight mounting section
33 Long round hole as a large through hole
34 Round holes as small through holes

Claims (1)

  In a windbreak snow fence in which a plurality of vertical windbreak snowboards are arranged in a row vertically to form a fence against the windward in winter, between vertically-arranged support columns. From the height of about 2/3 of the height, the bottom is made of a non-perforated plate, and the windproof snowboards of the upper and lower levels, from about 2/3 of the height of the fence to about 5/6, have a vertical cross-sectional shape. Is formed of a line-symmetric bulge and linear attachment portions at both ends of the bulge, and one of the line-symmetric bulges has a straight or curved inclined surface inclined upward toward the windward, The inclined surface is provided with a number of through holes extending in the longitudinal direction of the windbreak snowboard, the opposite side of the bulging portion is not perforated, and the opening ratio of the entire upper and lower stages is about 20%, and the fence height is about 2%. When the wind blown from the windward to the height of about 5/6 from the height of / 3 passes through the through hole of the inclined surface of the windbreak snowboard, the direction of the airflow is changed upward. The upper and lower windbreak snowboards from the height of about 5/6 of the fence to the upper end are composed of a bulging portion whose vertical cross section is line symmetrical and a straight mounting portion at both ends of the bulging portion. One of the symmetrical bulges has a straight or curved inclined surface that is inclined upward toward the windward side, and a large number of large through holes are provided on the inclined surface in the longitudinal direction of the windbreak snowboard, thereby expanding the bulge. A small through hole is provided on the opposite side of the projecting portion so that the opening ratio of the entire upper stage is about 40%, and the wind blowing from the windward to the height from about 5/6 of the fence height to the upper end is the windproof A windbreak snow fence that changes the direction of the airflow upward when passing through the large and small holes on the inclined surface of the snowboard.